The present invention relates generally to a semiconductor light-emitting device of array type. More particularly, the invention relates to a semiconductor light-emitting device having a monolithic array of double-heterojunction regions each including a light-emitting portion for emitting light from the end face thereof.
Applied Physics Letters, Vol. 41, No. 11, pp. 1040 to 1042, published on Dec. 1, 1982, discloses an exemplary semiconductor light-emitting device having an individually addressable monolithic array of double-heterojunction light-emitting regions each including a light-emitting portion for emitting light from the end face thereof, wherein the light-emitting portions are arrayed in a row and electrically separated from each other so as to enable individual addressing thereto.
Such a conventional semiconductor light-emitting device of array type can be used as a light-source element of a printing head in an optical printer such as laser printer, since the light-emitting portions can be addressed individually.
However, the above-mentioned conventional device has the following defects.
Namely, when all the light-emitting portions of the above-mentioned device of array type are activated to emit light, a near visual pattern of light which is formed outside the light-emitting portions is characterized in that light spots each having a diameter of about 3 .mu.m are aligned at the interval of about 150 .mu.m in a direction along the array of light-emitting portions.
For this reason, when such a conventional semiconductor light-emitting device of array type is used as a light-source element of a printing head and is used for forming a so-called black solid printed portion, a region between respective two successive light-emitting portions tend to be underexposed, resulting in the formation of an insufficient or uneven image as the solid portion.